Endpoint booster systems

ABSTRACT

An endpoint booster transports an optical signal from inside of a plasma etch chamber through a viewport to an optical cable outside of the plasma etch chamber. The optical signal is analyzed to determine an endpoint of a plasma process. The endpoint booster inhibits process byproducts from accumulating on the viewport during the plasma process, which increases the time between chamber cleanings. The reduction in chamber downtime for cleaning increases production throughput.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57.

BACKGROUND OF THE INVENTION

Traditionally, plasma etch processes have been controlled by rigorousattention to parameters such as RF power, gas mixture composition andflow, chamber pressure, substrate temperature and load size.Unfortunately, the interaction of these parameters with respect to theplasma chemistry is complex, making process control difficult. OpticalEmission Spectroscopy (OES) techniques offer an opportunity to monitorplasma chemistry directly and in real time. By viewing the dischargethrough a window in the chamber, this non-invasive technique can beapplied to the many types of etching systems currently employed withoutany perturbation of the etch process. A fiber optic cable transports theoptical signal from the window in the chamber to optical spectrometerfor analysis.

SUMMARY

When the window becomes obscured with the byproducts of the process, theoptical signal is no longer reliable. Cleaning the window can result insignificant production downtime. In an embodiment, an endpoint boosterinstalled in the chamber next to the window inhibits byproducts of theprocess from being deposited onto the window.

Certain embodiments relate to an endpoint booster having a front side, aback side, and an outer diameter, and comprising an aperture configuredto channel the endpoint signal from a vacuum etch chamber to a fiberoptic cable. The vacuum etch chamber includes a view port window, wherethe back side of the end point booster is next to a vacuum side of theviewport window and the front side is exposed to an interior of thevacuum etch chamber. The endpoint booster is configured to increase timebetween chamber cleanings due to byproduct deposit on the viewportwindow during semiconductor wafer etching in the vacuum etch chamber.

In an embodiment, the aperture includes a first diameter and a seconddiameter. In another embodiment, the aperture further includes aplurality of clustered holes extending through the endpoint booster fromthe front side to the back side. In a further embodiment, the pluralityof clustered holes include a first ring of holes around the firstdiameter. In a yet further embodiment, the plurality of holes furtherincludes a second ring of holes around the second diameter.

In an embodiment, the plurality of clustered holes form a plurality ofconcentric circles about a center point of the endpoint booster, whereeach clustered hole has a diameter of approximately 1/16″ and theplurality of clustered holes is configured to form at least first andsecond concentric circles such that the first concentric circle has thefirst diameter and the second concentric circle has the second diameter.In another embodiment, the plurality of clustered holes form a honeycombpattern. In a further embodiment, the plurality of clustered holes forma Gatling pattern.

In an embodiment, the aperture further includes a first length and asecond length such that the front side of the endpoint booster includesa first opening along the first length corresponding to the firstdiameter and the back side of the endpoint booster includes a secondopening along the second length corresponding to the second diameter. Inanother embodiment, the second diameter is larger than the firstdiameter.

According to some implementations, the disclosure relates to a systemfor etching a semiconductor wafer where the system comprises a vacuumetch chamber including a viewport window having an atmospheric side anda vacuum side, and a fiber optic cable optically coupled to theatmospheric side of the viewport window, where the fiber optic cable isconfigured to receive and transmit an endpoint signal. The systemfurther comprises an endpoint booster having a front side, a back side,an outer diameter, and an aperture configured to channel the endpointsignal from the vacuum etch chamber to the fiber optic cable. The backside of the endpoint booster is configured to be installed next to thevacuum side of the viewport window in the vacuum etch chamber and thefront side of the endpoint booster is configured to be exposed to aninterior of the vacuum etch chamber.

In an embodiment, the endpoint booster increases time between chambercleanings due to byproduct deposit on the viewport window duringsemiconductor wafer etching in the vacuum etch chamber. In anotherembodiment, the viewport window transmits the endpoint signal to thefiber optic cable. In an embodiment, the aperture includes a firstdiameter and a second diameter.

In an embodiment, the aperture further includes a first length and asecond length such that the front side of the endpoint booster includesa first opening along the first length corresponding to the firstdiameter and the back side of the endpoint booster has a second openingalong the second length corresponding to the second inner diameter. Inanother embodiment, the second diameter is larger than the first innerdiameter. In a further embodiment, the first and second diameters areapproximately the same. In a yet further embodiment, the first andsecond openings are concentric.

In an embodiment, the aperture includes a plurality of clustered holesextending through the endpoint booster from the front side to the backside and forming a plurality of concentric circles about a center pointof the endpoint booster, where a first concentric circle has the firstdiameter and a second concentric circle has the second diameter.

In accordance with some embodiments, the disclosure relates to a methodto etch a semiconductor wafer in a vacuum etch chamber. The methodcomprises transmitting an optical signal through an aperture in anendpoint booster to a fiber optic cable during a plasma etching processof the semiconductor wafer. The vacuum etch chamber includes a viewportwindow having a vacuum side and an atmospheric side, and the fiber opticcable is optically coupled to the atmospheric side of the viewportwindow. The aperture is configured to channel the optical signal fromthe vacuum etch chamber to the fiber optic cable. The endpoint boosterhas a front side and a back side, where the back side of the endpointbooster is installed next to the vacuum side of the viewport window inthe vacuum etch chamber and the front side of the endpoint booster isexposed to an interior of the vacuum etch chamber

In an embodiment, the method further comprises installing the endpointbooster in the vacuum etch chamber, plasma etching a semiconductor waferin the vacuum etch chamber, and ending the plasma etching when theoptical signal reaches a first threshold. In another embodiment, themethod further comprises cleaning the vacuum etch chamber when strengthof the endpoint signal is below a second threshold due to byproductdeposit on the viewport window during the plasma etching of thesemiconductor wafer in the vacuum etch chamber. In a further embodiment,cleaning the vacuum etch chamber includes replacing the viewport window.In a yet further embodiment, the endpoint booster increases time betweenchamber cleanings.

In an embodiment, aperture includes a first diameter and a seconddiameter. In another embodiment, the endpoint booster further includes afirst length and a second length such that the front side of theendpoint booster includes a first opening along the first lengthcorresponding to the first diameter and the back side of the endpointbooster has a second opening along the second length corresponding tothe second diameter. In another embodiment, the aperture includes aplurality of clustered holes extending through the endpoint booster fromthe front side to the back side and forming a plurality of concentriccircles about a center point of the endpoint booster, a first concentriccircle having the first diameter and a second concentric circle havingthe second diameter.

For purposes of summarizing the invention, certain aspects, advantages,and novel features of the invention have been described herein. It is tobe understood that not necessarily all such advantages may be achievedin accordance with any particular embodiment of the invention. Thus, theinvention may be embodied or carried out in a manner that achieves oroptimizes one advantage or group of advantages as taught herein withoutnecessarily achieving other advantages as may be taught or suggestedherein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a fabrication system including a plasmaetch apparatus having one or more features described herein.

FIG. 2A is a schematic drawing of an endpoint booster for opticalendpoint detection, according to certain embodiments.

FIGS. 2B, 2C, and 2D illustrate a perspective view, a front view, and aback view, respectively, of the endpoint booster of FIG. 2A, accordingto certain embodiments.

FIG. 3 is a schematic diagram of an endpoint booster installed in achamber viewport, according to certain embodiments.

FIG. 4 is a table showing examples of RF Hour Data for a through wafervia etch chamber using an embodiment of an endpoint booster.

FIG. 5A illustrates byproduct buildup from an etch process on anembodiment of an endpoint booster installed in an etch chamber,according to certain embodiments.

FIG. 5B illustrates byproduct buildup from an etch process on a viewportwindow in an etch chamber with an endpoint booster, according to certainembodiments.

FIGS. 5C and 5D illustrate byproduct buildup from an etch process onviewport windows in etch chambers without an endpoint booster, accordingto certain embodiments.

FIG. 6A is a schematic drawing of an endpoint booster for opticalendpoint detection, according to certain embodiments.

FIG. 6B illustrates perspective views of the embodiment of the endpointbooster of FIG. 6A, according to certain embodiments.

DETAILED DESCRIPTION

The features of the systems and methods will now be described withreference to the drawings summarized above. Throughout the drawings,reference numbers are re-used to indicate correspondence betweenreferenced elements. The drawings, associated descriptions, and specificimplementation are provided to illustrate embodiments of the inventionsand not to limit the scope of the disclosure.

FIG. 1 schematically depicts a plasma process apparatus that can be apart of a semiconductor fabrication system 100. The plasma processapparatus comprises a chamber 110, upper and lower electrodes 114, 116,and a radio frequency (RF) source 120. In an embodiment, the chamber 110comprises a vacuum chamber 110. The electrodes 114, 116 and the RFsource 120 are located inside 128 of the vacuum chamber 110. In anexample of parallel-plate configuration, RF power 120 is depicted asbeing applied to the upper electrode 114 while the lower electrode 116,which is depicted as a platen in FIG. 1, is typically electricallygrounded. A semiconductor wafer 118 is shown positioned on the platen116 and subjected to plasma 122 due to the applied RF power 120.

It will be understood that the plasma process apparatus 100 can beconfigured in other ways. For example, other plasma process systems canhave the RF power 120 applied to the platen 116 and the upper electrode114 grounded. A number of other configurations are also possible. Forexample, the plasma process apparatus 100 could be a reactive-ionetching (RIE) system, a sputtering tool, and the like.

In an embodiment, the plasma process apparatus performs athrough-wafer-via (TWV) etch as part of the semiconductor fabricationsystem 100. During plasma etching, endpoint detection is used to controlthe amount of etching. In one embodiment, optical emission spectroscopy(OES) is used to monitor the optical endpoint spectrum and thesemiconductor fabrication system 100 further comprises a fiber opticcable 124 and an optical spectrometer 126, which are located outside 130of the vacuum chamber 110.

OES etch endpoint detection in a plasma process relies on the changingplasma fluorescence as the elemental composition of the exposed surfacechanges. Different chemical materials emit different wavelengths as theyare brought into the plasma 122, which varies the color of the plasma122. The light emission from the plasma 122 is measured using theoptical spectrometer 126. The endpoint signal is transferred to thespectrometer 126 via the fiber optic cable 124. The fiber optic cable124 transfers the endpoint signal from the vacuum chamber 110 through aviewport 112 on the vacuum chamber 110 to the optical spectrometer 126.

In order to achieve a consistent endpoint signal, the optical signalmonitored by the optical spectrometer 126 needs to be robust during theetching process. In an embodiment, byproduct from the plasma processbuilds up on the viewport 112, which can reduce the endpoint signaltransmitted through the viewport 112 into the fiber optic cable 124. Asetch byproducts collect on the viewport 112, the endpoint signal becomesweaker, which can hinder the ability to monitor the etch or other plasmaprocesses. In an embodiment, the endpoint signal is weak when it isbelow a threshold. In another embodiment, the endpoint signal is weakwhen its power level is below a threshold.

One way of maintaining a clean viewport is to change the viewport 112when it becomes dirty. Changing the viewport 112 involves venting thevacuum chamber 110, which can entail several hours of tool downtime andrequalification of the chamber 110 before it is returned to production.

In an embodiment, the semiconductor fabrication system 100 furthercomprises an endpoint booster 200 installed in the vacuum chamber 110.In an embodiment, the vacuum chamber 110 further comprises the endpointbooster 200 installed in the viewport 112. The use of the endpointbooster 200 in the vacuum chamber 110 extends the radio frequency (RF)hours between chamber cleans. This reduces the chamber downtime, whichin turn, increases production throughput. Reducing the number of chambercleans further reduces costs for replacing dirty parts and cleaningreusable parts associated with the vacuum chamber 110.

FIG. 2 is a schematic drawing of an embodiment of the endpoint booster200 for optical endpoint detection. In an embodiment, the endpointbooster 200 comprises a cylinder having an outer diameter D3 and alength L, and comprising a first opening or aperture 202 having adiameter d1 on one end that transitions to a second opening or aperture204 having a diameter d2. In an embodiment, the transition between thefirst aperture 202 and the second aperture 204 occurs at a mid-pointalong the length L. In other embodiments, the transition occurs at otherlocations along the length L. In another embodiment, the transitionbetween the first aperture 202 and the second aperture 204 occursgradually along the length L.

In one embodiment, the endpoint booster 200 comprises an aluminumcylinder, approximately 0.60″ long, with an approximately 1.5″ outerdiameter, and an approximately ½″ inner diameter opening or aperture 202on one end which transitions to an approximately ¼″ inner diameteropening 204.

In an embodiment, the endpoint booster 200 further comprises a removalport 206. In an embodiment, the removal port 206 comprises a threadedhole that permits an operator to thread a removal device into theremoval port 206 and engage the endpoint booster 200 so as to be able toremove the endpoint booster 200 from the wall of the vacuum chamber 110.

In other embodiments, the endpoint booster 200 comprises othermaterials, such as stainless steel, anodized aluminum, ceramic,polycarbonate, robust plastic compounds, quartz, borosilicate glass, andthe like. In an embodiment, the outer diameter D of the endpoint booster200 can be more or less than approximately 1.5″ and the length L can bemore or less than approximately 0.60″ to accommodate vacuum chambers 110with different wall thicknesses and different viewport dimensions. Inother embodiments, the diameter d1 of the first aperture 202 can be moreor less than ½″ and the diameter d2 of the second aperture 204 can bemore of less than ¼″. In an embodiment, the diameter d1 of the firstaperture 202 can be approximately equal to the diameter d2 of the secondaperture 204.

FIGS. 2B, 2C, and 2D illustrate a perspective view, a front view, and aback view, respectively, of the endpoint booster of FIG. 2A. FIGS. 2Band 2D illustrate the apertures 202 and 204 and show the side of theendpoint booster 200 that is placed away from the inside 128 of thevacuum chamber 110. FIG. 2C illustrates the smaller aperture 204 andshows the side of the endpoint booster 200 that is exposed to the vacuumand plasma in the vacuum chamber 110.

FIG. 3 is a schematic diagram of the endpoint booster 200 installed inthe viewport 112, according to an embodiment. The fiber optic cable 124is installed in the viewport 112 to receive and transmit the endpointsignal. The endpoint booster 200 fits within the vacuum chamber 110 suchthat no vacuum seals are broken, therefore not affecting the integrityof the vacuum chamber 110.

The viewport 112 within a chamber wall 304 of the vacuum chamber 110comprises an outer viewport window 306 and an inner viewport window 308.The endpoint booster 200 is placed inside 128 of the vacuum chamber 110such that the endpoint booster is next to the inner viewport window 308.In an embodiment, the endpoint booster 200 is installed within theviewport 112 of the vacuum chamber 110 flush to the inner viewportwindow 308. The first aperture 202 of the endpoint booster 200 isinstalled toward the inner viewport window 308, and the second aperture204 of the endpoint booster 200 is installed toward the interior 128 ofthe vacuum chamber 110. The second aperture 204 comprises an opticalsignal opening and is used to control the field of view of the fiberoptical cable 124. The fiber optic cable 124 is installed outside 130 ofthe vacuum chamber 110 onto the outer viewport window 306. The endpointbooster's second aperture 204 allows the light from the plasma 122 tochannel to the fiber optic cable 124 through the outer viewport window306, while minimizing the exposed surface area of the inner viewportwindow 308 to the process byproducts. The second aperture 204 ismachined to prevent off-axis reflections, in an embodiment.

In other embodiments, the outer diameter and length of the endpointbooster 200 can be modified to match the vacuum chamber viewportdimensions. In an embodiment, the second aperture 204 of the endpointbooster 200 can be configured to match the outer diameter of the fiberoptic cable 302. In an embodiment, the first aperture 202 of theendpoint booster 200 can be configured to match the outer diameter ofthe fiber optic cable 302.

FIG. 4 is a table illustrating examples of RF Hour Data for a throughwafer via etch chamber 110 using an embodiment of the endpoint booster200. In an embodiment, the chamber cleaning specification or the timebetween chamber cleanings is set at 95 hours, whereas the previousspecification was 60 hours, due to the improvements introduced by theendpoint booster 200.

FIG. 5A illustrates byproduct buildup from an etch process on anembodiment of the endpoint booster 200 installed in the vacuum chamber110.

FIGS. 5B, 5C, and 5D illustrate byproduct buildup from an etch processin the vacuum chamber 110. Inner viewport window 502 was used in an etchprocess in conjunction with an embodiment of the endpoint booster 200.Viewport windows 504 and 506 are additional viewports not used fortransmitting the endpoint signal to the fiber optic cable 124, but theyare indicative of the byproduct buildup that occurs during the etchprocess. Due to the etch process, the viewport windows 504, 506 becomecovered in a film created by the process byproducts. Viewport window 906includes a heavy deposit of etch byproduct in the center.

In contrast, endpoint booster 200 covered inner viewport window 502during the etch process. Inner viewport window 502 has a slight whitishdeposit in the center, corresponding to the small aperture 204 facingthe inside 128 of the vacuum chamber 110. Less etch byproduct isdeposited onto the inner viewport window 902 due to the endpoint booster200.

FIG. 6A is a schematic drawing of another embodiment of an endpointbooster 600 having a diameter D4 and a length L and comprising anaperture 602 for optical endpoint detection. The aperture 602 of theendpoint booster 600 comprises a plurality of clustered holes 604arranged in concentric circles having diameters d1, d2, and d3 measuredfrom the center point of the endpoint booster 600. In other embodiments,the aperture 602 of the endpoint booster 600 comprises a plurality ofholes or orifices 604 that are congregated around or within the aperture602. The plurality of clustered holes extend from a first side of theendpoint booster 600 to a second side of the endpoint booster 600 alongthe length L. In an embodiment, the diameter of each hole of theplurality of clustered holes 604 does not change along the length L. Inanother embodiment, each hole of the plurality of clustered holes istapered. In a further embodiment, the diameter of each hole of theplurality of clustered holes is approximately the same. In a yet furtherembodiment, the diameter of each hole in each concentric circle is thesame, but the diameter of the holes comprising each concentric circlevaries from the diameter of the holes in the other concentric circles.

In the illustrated embodiment of FIG. 6, the endpoint booster 600comprises an aluminum cylinder approximately 0.60″ long and having anouter diameter of approximately 1.5″ with 27 holes, each hole having adiameter of approximately 1/16″. The 1/16″ diameter holes are arrangedas follows: fifteen (15) holes form a circle having approximately a0.375″ diameter d3, nine (9) holes form a circle having approximately a0.22″ diameter d2, and three (3) holes form a circle havingapproximately a 0.086″ diameter d1.

In other embodiments, the outer diameter D4 and length L of the endpointbooster 600 can be modified to match the vacuum chamber viewportdimensions. The number of concentric circles forming the aperture 602can be more or less than three. The clustered holes 604 of the endpointbooster 600 can be larger or smaller than 1/16″ and can be arranged inother patterns, such as a honeycomb pattern, a Gatling pattern, taperedholes, and the like. The number of holes 604 in the aperture 602 of theendpoint booster 600 can be varied to suit the type of etch being usedin the vacuum chamber 110 and can be varied to suit the endpointdetection criteria.

The endpoint booster 600 further comprises a removal port 606 similar tothe removal port 206.

FIG. 6B illustrates perspective views of the embodiment of the endpointbooster 600 of FIG. 6.

The endpoint booster 200, 600 improves time between chamber cleans. Theendpoint booster 200, 600 is a passive solution, which is practical in aproduction environment. It is easy to manufacture, inexpensive tomanufacture, and easy to use.

Embodiments of the optical signal endpoint booster 200, 600 can beutilized in any vacuum chamber 110 to monitor the endpoint signal. Theoptical signal endpoint booster 200, 600 can be used to in applicationsthat monitor the plasma for etching, deposition, residual gas analysis,and the like. Types of plasma include, for example, low density plasmas(Magnetically Enhanced Reactive Ion Etching (MERIE) and Single FrequencyCapacitively Coupled Plasmas (SF-CCP)) and in high density plasmas(Inductively Coupled Plasmas (ICP), Ultra High Frequency CapacitivelyCoupled Plasmas (UHF-CCP), Double Frequency Capacitively Coupled Plasmas(DF-CCP) and Electron Cyclotron Resonance (ECR) Plasmas), ion-ionplasmas, and the like.

The endpoint booster 200, 600 is a passive and economical design. Theendpoint booster 200, 600 is sturdy, compact, easy to clean, and easy toinstall with no moving parts. The endpoint booster 200, 600 is made ofmaterial that is compatible with the tool and process. The endpointbooster 200, 600 can be made of a material that has a long life withinthe tool and process. For example, an aluminum booster is installed inan etch chamber to be used for a through-wafer-via (TWV) chlorine etch,nitride fluorine etch, BCl3/Cl2 etch, other types of etches, plasmaprocesses, and the like that use an optical endpoint detection.

Embodiments of the endpoint booster 200, 600 could be used inapplications within vacuum chambers 110 that channel light to a fiberoptic, such as, for example, optical monitoring in semiconductorprocessing and endpoint detection of thin film deposition. The endpointbooster 200, 600 could also be used in other applications that requirethe monitoring of an optical signal. The endpoint booster 200, 600 couldalso be used in non-vacuum applications. The endpoint booster 200, 600is designed for applications where the window or viewport 112 becomescoated with byproduct from the process. The installation of the endpointbooster 200, 600 reduces the amount of deposition that collects on theviewport 112, and provides better viewing of the plasma or other processwithin the chamber 110.

Terminology

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense, as opposed to anexclusive or exhaustive sense; that is to say, in the sense of“including, but not limited to.” The word “coupled”, as generally usedherein, refers to two or more elements that may be either directlyconnected, or connected by way of one or more intermediate elements.Additionally, the words “herein,” “above,” “below,” and words of similarimport, when used in this application, shall refer to this applicationas a whole and not to any particular portions of this application. Wherethe context permits, words in the above Detailed Description using thesingular or plural number may also include the plural or singular numberrespectively. The word “or” in reference to a list of two or more items,that word covers all of the following interpretations of the word: anyof the items in the list, all of the items in the list, and anycombination of the items in the list.

Moreover, conditional language used herein, such as, among others,“can,” “could,” “might,” “can,” “e.g.,” “for example,” “such as” and thelike, unless specifically stated otherwise, or otherwise understoodwithin the context as used, is generally intended to convey that certainembodiments include, while other embodiments do not include, certainfeatures, elements and/or states. Thus, such conditional language is notgenerally intended to imply that features, elements and/or states are inany way required for one or more embodiments or that one or moreembodiments necessarily include logic for deciding, with or withoutauthor input or prompting, whether these features, elements and/orstates are included or are to be performed in any particular embodiment.

The above detailed description of embodiments of the invention is notintended to be exhaustive or to limit the invention to the precise formdisclosed above. While specific embodiments of, and examples for, theinvention are described above for illustrative purposes, variousequivalent modifications are possible within the scope of the invention,as those skilled in the relevant art will recognize. For example, whileprocesses or blocks are presented in a given order, alternativeembodiments may perform routines having steps, or employ systems havingblocks, in a different order, and some processes or blocks may bedeleted, moved, added, subdivided, combined, and/or modified. Each ofthese processes or blocks may be implemented in a variety of differentways. Also, while processes or blocks are at times shown as beingperformed in series, these processes or blocks may instead be performedin parallel, or may be performed at different times.

The teachings of the invention provided herein can be applied to othersystems, not necessarily the system described above. The elements andacts of the various embodiments described above can be combined toprovide further embodiments.

While some embodiments of the inventions have been described, theseembodiments have been presented by way of example only, and are notintended to limit the scope of the disclosure. Indeed, the novel methodsand systems described herein may be embodied in a variety of otherforms; furthermore, various omissions, substitutions, and changes in theform of the methods and systems described herein may be made withoutdeparting from the spirit of the disclosure. The accompanying claims andtheir equivalents are intended to cover such forms or modifications aswould fall within the scope and spirit of the disclosure.

1. An endpoint booster having a front side and a back side, andcomprising an aperture configured to channel an endpoint signal from avacuum etch chamber to a fiber optic cable, the back side of theendpoint booster configured to be installed next to a vacuum side of aviewport window within a wall of the vacuum etch chamber and the frontside of the endpoint booster configured to be exposed to an interior ofthe vacuum etch chamber, the front side including a removal portconfigured to receive a removal tool thereby permitting an operator toremove the endpoint booster from within the vacuum etch chamber to cleanthe viewport window.
 2. The endpoint booster of claim 1 wherein theendpoint booster is configured to increase time between chambercleanings due to byproduct deposit on the viewport window duringsemiconductor wafer etching in the vacuum etch chamber.
 3. The endpointbooster of claim 1 wherein the aperture further includes a first lengthand a second length such that the front side of the endpoint boosterincludes a first opening along the first length corresponding to a firstdiameter and the back side of the endpoint booster includes a secondopening along the second length corresponding to a second diameter. 4.The endpoint booster of claim 3 wherein the second diameter is largerthan the first diameter.
 5. The endpoint booster of claim 1 wherein theremoval port includes a threaded hole that permits the operator tothread the removal tool into the removal port and engage the endpointbooster.
 6. The endpoint booster of claim 1 wherein the aperture extendsfrom the front side to the back side.
 7. The endpoint booster of claim 1wherein the second diameter is approximately 0.50 inches and the firstdiameter is approximately 0.25 inches.
 8. The endpoint booster of claim1 wherein the endpoint booster is cylindrical, an outer diameter of theendpoint booster is approximately 1.5 inches, and a length of theendpoint booster is approximately 0.60 inches.
 9. The endpoint boosterof claim 1 wherein the aperture further includes a first diameter and asecond diameter such that the front side of the endpoint boosterincludes the first diameter and the back side of the endpoint boosterthe second diameter.
 10. The endpoint booster of claim 9 wherein atransition between the first diameter and the second diameter occursgradually along a length of the endpoint booster.
 11. A system foretching a semiconductor wafer, the system comprising: a vacuum etchchamber including a viewport window having an atmospheric side and avacuum side; a fiber optic cable optically coupled to the atmosphericside of the viewport window, the fiber optic cable configured to receiveand transmit an endpoint signal; and an endpoint booster having a frontside and a back side, and comprising an aperture configured to channelan endpoint signal from a vacuum etch chamber to a fiber optic cable,the back side of the endpoint booster configured to be installed next toa vacuum side of a viewport window within a wall of the vacuum etchchamber and the front side of the endpoint booster configured to beexposed to an interior of the vacuum etch chamber, the front sideincluding a removal port configured to receive a removal tool therebypermitting an operator to remove the endpoint booster from within thevacuum etch chamber to clean the viewport window.
 12. The system ofclaim 11 wherein the endpoint booster is configured to increase timebetween chamber cleanings due to byproduct deposit on the viewportwindow during semiconductor wafer etching in the vacuum etch chamber.13. The system of claim 11 wherein the aperture further includes a firstlength and a second length such that the front side of the endpointbooster includes a first opening along the first length corresponding toa first diameter and the back side of the endpoint booster includes asecond opening along the second length corresponding to a seconddiameter.
 14. The system of claim 13 wherein the second diameter islarger than the first diameter.
 15. The system of claim 11 wherein theremoval port includes a threaded hole that permits the operator tothread the removal tool into the removal port and engage the endpointbooster.
 16. The system of claim 11 wherein the aperture extends fromthe front side to the back side.
 17. The system of claim 11 wherein thesecond diameter is approximately 0.50 inches and the first diameter isapproximately 0.25 inches.
 18. The system of claim 11 wherein theendpoint booster is cylindrical, an outer diameter of the endpointbooster is approximately 1.5 inches, and a length of the endpointbooster is approximately 0.60 inches.
 19. The system of claim 11 whereinthe aperture further includes a first diameter and a second diametersuch that the front side of the endpoint booster includes the firstdiameter and the back side of the endpoint booster the second diameter.20. The system of claim 19 wherein a transition between the firstdiameter and the second diameter occurs gradually along a length of theendpoint booster.